The art of the present invention relates to blower housings for blower fan assemblies used in HVAC systems although the present invention can also be utilized in other industries employing blower systems. The improved blower housing of the present invention incorporates a uniquely formed joint or seam having a combination locking tab and slot which provides positive lockup of the blower housing side walls to a blower housing wrapper wall sheet. The present art essentially eliminates unintentional separation of the formed unit both prior to final manufacturing assembly and during its entire useful service life.
Blower housings of the type pertaining to the present invention are typically employed in forced air heating furnaces or air conditioners. In most cases, the blower is assembled in the interior of the HVAC equipment. Ambient air is blown by the blower over heat exchangers that heat or cool the air. The heated or cooled air is then forced from the furnace/air conditioner by the blower. A typical blower housing contains a cylindrical blower fan and is constructed from a pair of housing side walls spaced at opposite lateral sides of the blower housing and a wrapper wall sheet that is connected around peripheral edges of the two side walls. The wrapper wall sheet spaces the two side walls laterally from each other and gives the blower housing a general cylindrical configuration well suited for containing the cylindrical blower fan.
With the commercially manufactured prior art, the side walls and the wrapper wall sheet of a conventional non-welded blower housing assembly are typically either attached by a crimped folded over seam joint or, as in the case of applicant's prior U.S. Pat. No. 5,221,183, a two-sectional angled seam joint. Both of the prior art attachment types, use seams which are now known to function as an essential slip-joint allowing movement and/or separation of the assembly's side walls and wrapper wall sheet. This movement and/or separation problem is particularly apparent during final assembly of the complete blower unit. (i.e. motor and blower fan installation) When separated, the side walls and the wrapper wall sheet are no longer usable thereby causing significant operating and yield loss (e.g. scrap) during the manufacturing or repair process. Prior art blower housings attempt to address the blower housing separation problem by utilizing either spot welds and/or auxiliary fasteners, such as end screws, neither of which is satisfactory since both increase the manufacturing cost of the blower housing.
The combination locking tab and slot seam of Applicant's improved blower housing allows for the joining of different materials and/or different material thicknesses. The seam versatility of the present invention, which is adaptable to material variations, can provide significant engineering advantages such as thicker material utilization on the load bearing side wall (which typically supports the motor and wheel assembly) and thinner material utilization on the non-load bearing side wall and the wrapper wall sheet. Also, a greater size range of blower housings can be manufactured in the same assembly machines with less cycle time and without changeover or modification to the equipment, thereby reducing the manufacturing cost of the blower housings. The ability to join the blower housing dissimilar material or material of varying thickness is desired since the assembly machine can be built easier and less expensively. Accordingly, one assembly or forming machine can be programmed to not only make a larger size range of blower housings but also to produce the blower housings faster and therefore less expensively.
The combination locking tab and slot seam of the present invention further provides that the locking tab is substantially flush with the outside surface of the wrapper wall sheet when finally engaged in the slot regardless of orientation or material variation. This ensures a substantially smooth seam throughout its entire formed length.
Accordingly, it is an object of the present invention to provide an improved blower housing and method of manufacture which provides a positive lockup of blower side walls to a blower housing without the use of welds or fasteners.
Another object of the present invention is to provide an improved blower housing and method of manufacture which is environmentally friendly by allowing reuse of the blower side walls and wall sheet when separated without the necessity of discarding said components.
A further object of the present invention is to provide an improved blower housing and method of manufacture which is capable of joining different materials and materials of different thicknesses.
A still further object of the present invention is to provide an improved blower housing and method of manufacture which is easy and economical to manufacture in a variety of sizes with the same assembly machines.
A yet further object of the present invention is to provide an improved blower housing and method of manufacture having locking tabs mating with slots which are substantially flush with the outside surface of the wrapper wall sheet regardless of orientation or material variation in order to provide a substantially smooth seam.